The Measurement And Analysis Of The Three-dimensional Geometry Of The Adult Proximal Humeri

Background and objectiveWith the hard work of many shoulder researchers, the modern shoulder prosthesis have been improved from the first generation-monoblock prosthesis to the fourth genera-tion-3-dimensional prosthesis. The most important idea of the fourth generation prosthesis is anatomical reconstruction of the proximal humerus and individual prosthesis implantation. The realization of the idea requires on an appropriate measurement method which should sa-tisfy three requests:firstly, accurate measurement and analysis of the three-dimensional geo-metry of the proximal humerus; secondly, a large sample research; thirdly, an invidual mea-surement can be done preoperatively to help the implantation of prosthesis. At present, there are a great deal of parameters of the proximal humerus and different measurement methods. The different measurement methods and definition lines result in great dissagreements in the measurement which may bring lots of trouble in design and implantation of shoulder prosthe-sis. The appropriate measurement method has not been reported so far.We managed to measure the three-dimensional geometry of the proximal humeri of some specimens with postprocessing technique of multislice spiral CT(MSCT) successfully, and found that the measurement methods have some advantages comparing with the previous ones: simple, no special position requirement during scanning,all values of these parameters could be achieved in the workstation of the MSCT. But, the accuracy of this imageologic measurement method was not verified by the anatomic measurement, and, the method was not used to meaure the three-dimensional geometry of the proximal humeri of health adult. The present study aimed to explore the accuracy of the imageology measurement method, and analyze possible sources of error; to design a reliable and simple measurement method, and meaure the three-dimensional geometry of the proximal humeri of health adult, to find whether there are difference between female and male ,between left and right shoulder.Methods Twenty cadaveric humeri were used to verify the methods'accuracy by three steps. First, all humeri were scanned by a 16-slice spiral CT scanner, and their head retroversion angle was measured.then, all humeri head retroversion angle were measured anatomically. Finally, these humeri with a marked anatomic neck were scanned by a 16-slice spiral CT scanner and their angles were measured. The measurement parameter include: RA(Retroversion angle), NSA(Neck shaft angle), ASD(Articular surface diameter), HH(Head height). The difference of the measurement value and images of these 3 steps were analyzed to verify the reliability of our method and find the source of error.There were 100 healthy volunteers (100 left,100 right; 59 females, 41 males). the the three-dimensional geometry of the proximal humeri were measured by two osteopaths using volume rendering technique with MSCT twice, and the average values were analysed by spss13.0 to explore the difference between female and male, left and right shoulder. The measurement parameter include: ASD, ROC (Radius of curvature), width of bone medullar cavity, RA, NSA, MO(Medial offset), PO(Posterior offset).Results1. There were no significant differences in RA, NSA, ASD, HH(cornal view) between imageology measurement and anatomical measurement. There were significant difference in HH(axial view).2. There were no significant differences in ASD(cornal and axial view), and ROC(axial view) between bilateral shoulders. There were significant differences in ROC(cornal view) between bilateral shoulders. The average values of ASD and ROC in the cornal view were larger than that in the axial view. There were significant differences in ASD and ROC be-tween female and male, the average value of male was larger than that of female's.3. There were significant difference in almost all of the measurement values of the me-dullary cavity width between bilateral shoulders.In the same deck, the medullary cavity width in the cornal view were bigger than that in the sagital view. The width of the medullary cavity decreased gradually from the proximal part to the distal part of the medullary cavity. The me-dullary cavity width of male were bigger than that of females.4. There were no significant differences in NSA and PO between bilateral shoulders. There were significant differences in RA and MO between bilateral shoulders. The variation of RA is large. There were singnificant gender differences in RA and PO, the value of male's was larger than that of female's. PO was correlated with RA.Conclusion1. The present study have established an accurate, simple, and practical imageologic measurement method for measuring the three-dimensional geometry of the proximal humeral.2. In this study, we obtained some precise data of the three-dimensional geometry of the proximal humera, which would be a good reference for the design of the new generation proximal humeral prosthesis.3. There are significant side and gender differences in most parameters in this study. And the shape of the humeral articular and medullary cavity are irregular. Maybe, it's good for improving the clinic effect to evaluate the three-dimensional geometry of the proximal humerus precisely preoperation with the imagelogic measurement method of this study.4. There are correlation between some parameters: the humeral head and medullary cav-ity width of the proximal humerus, RA and PO. It's suggested that we should do some more research on the correlation.